Discharge lamp circuit



April 1945- c. H. HODGKINS 2,374,352

' DISCHARGE LAMP 0130111 Filed April 15, 1942 INVENTOR CH IIGDSAIIVJ" ATTORNEY Patented Apr. 24, 1 945 rice DISCHARGE LAMP CIRCUIT Charles H. Hodgkin's, Fair-field, Com, assignor to The Bryant Electric Company, Bridgeport, Oonn., a corporation of Connecticut Application April 15, 1942, Serial No. 439,042 Q The present invention relates to a system for controlling and operating discharge lamps of the fluorescent type, and has particular reference to such systems wherein a plurality of fluorescent lamps are subjectto a unified control so as toenable immediate starting of the lamps and at the same time minimize the stroboscopic effect normally existent in'lamps of this type.

It is well known in the art to operate two fluorescent lamps in parallel and to employ a condenser in series with one of the lamps so that they are operated out of phase with each other to thereby avoid or minimize the stroboscopic efl'ect otherwise resulting, and which also serves-to correct the overall power factor of the lamps. Heretofore in such circuits avery pronounced time delay has existed between actual energization of 4 Claims. (or. 315-103) a will become obvious to those skilled in the m by 7 reference to the accompanying drawing wherein: Fig. 1 is a atic view of the control system of thepresent invention and showing the circuit arrangement prior to 'energization of the I lamps;

Fig. 2 is a diagrammatic view identical to Fig.

. 1 but showing the position of the various ele-t the lamps and the initiation of a discharge 1 therein. 7 It is accordingly an object of the present invention to provide a control system for discharge lamps of the fluorescent type whereby a pair of parallel connected lamps may be immediately started following initial energization, thereby eliminating the time delay formerly required.

Another object of the present invention is the provision of a-system for controlling and operating discharge lamps of the fluorescent type wherein part of the auxiliary equipment is employed to cause immediate starting of the lamps following energization thereof, after which the same portion of the auxiliary equipment is em.- ployed to eliminate the stroboscopic eflect and to correct the power factor.

Another object of the present invention is the provision of a system for controlling and operating discharge lamps of the fluorescent type wherein a condenser is arranged to be connected in electrical parallel 'with the lamps upon initial energization of the lamps to cause immediate starting thereof, and upon starting of the lamps such condenser is connected by an automatic transfer switch in series with one of the lamps so as to correct the overall power factor and minimize the stroboscopic effect of the lamps.

A further object of the present invention is the provision of a system for controlling and oper-' atingdischarge lamps of the fluorescent type wherein an automaticallyoperable transfer switch is employed to connect a condenser, which is normally in parallel with the lamps for starting purposes, in a series relation with one of the lamps to minimize the stroboscopic effect and aid in power factor correction Still further objects of the present invention 55 ments during the "starting periodof the lamps, and

Fig. 3 is another diagrammatic viewidentical to Fig. 1 but showing the position of the various elements during operation" of the lamps with the actual path of current flow through the cirin electrical parallel relation with the lamps 5 and 6 during initial starting, and after the discharge has started in the lamps such transfer switch connects the condenser 8 in series relationship with one of the lamps 5 so asft'o impart a leading power factor thereto, while the remaining lamp 6 has a lagging power factor which thusminimizes the stroboscopic-effect otherwise ensuing and at the same time improves the overall power factor of the circuit arrangement.

By reference to the several figures, it will be noted that the transfer switch I is provided with a plurality of contacts 9, II, II, l2, l3, II, and Li,

with the contacts 9, III, and H being movable by a switch rod or the like I 6 connected to the arma- 40 ture ll of the transfer switch with such armature,

together with the switch rod 16; biased down wardly by a coil spring l8- aided by gravity.

Since as before mentioned, the figures of, the

drawing are identical except for the position ofthe transfer switch-l under starting and operating conditions, the system will be thus described. Referring, therefore, more particularly to Fig.

- 2 showing the arrangement of the circuit under starting conditions,- it will be noted that aninductance element It is provided which is arranged in series with the fluorescent lamp 5 by having one of its ends connected to one side of the source of supply Ll while the other end is a connected by a conductor 20 to the switch contacts l3 and I .4. Inasmuch as switch contact I! cuit being shown by the heavy lines in this figure.

temperature.

' means of a conductor 24 to one end of the magnetic winding 25 of the transfer switch I. From the other side of the filamentary electrode 23 a conductor 26 extends tothe contact I! of the transfer switch 'I and from a juncture in the conductor 28, a conductor 21 extends to one side of the condenser '8. The opposite side or plate of the condenser 8 is connected by a conductor 28 to contact 8 of the transfer switch, whichin the start" position is in engagement with contact l2, and this latter contact is connected by a conductor 29 to one end of the filamentary electrode 3ll of the lamp 5. The circuit is then completed from the opposite end ofthe filamentary electrode 30 to the opposite side of the source of supply L2 through conductor 32 and closed operating switch 33. The opposite end of the magnetic winding 25 is connected to the conductor 23 by means of a conductor 34 which thus connects this magnetic winding 25, as well as'the condenser 8, in electrical parallel relation with the discharge lamp 5.

' In addition, the lamp 6 is also connected to the source of supply Ll-L2 in electrical parallel with the discharge lam 5. Such circuit extends from one side of the source of supply L through a conductor 35 and an inductance element 36, to one end of the filamentary electrode. 31 of the lamp 8,

thence from the other end of such electrode through a conductor 38, closed contacts H and l 8, conductors 26 and 21 to the condenser 8, from the opposite side of this condenser through conductor '28, closed contacts 9 and I2, through conductor 28- toone end of filamentary electrode 39 of the discharge lamp 8; and since the other end of this latter electrode is connected to the conductor 32, the circuit is completed through the "closed switch 33 to the opposite side of the supply source L2.

Accordingly, upon closure-of switch 33, the full voltage of the source of supply Ll, L2 is immediately applied to the magnetic winding 25 of the transfer switch I; resulting 'in attraction of its armature with raising of rod l8 so as to position the various contacts in the manner as shown in Fig, 2. immediately completes a series heating circuit for the filamentary electrodes 23-38 of the discharge lamp 5 as well as'a similar circuit for the filamentary electrodes 31-39 of the discharge lamp 6 which rapidly heats all of the filamentary electrodes to an electron emitting At the same time'that the electrodes are being heated, the condenser 8, which is in electrical parallel with the lamps 5 and 6 (although included in' the'series heating circuit for the filamentary electrodes thereof)-, accumulates a charge and upon discharge thereof across the heated electrodes 23-38 and 31-39, this discharge voltage augments the-voltage of the supply source sufilciently to initiate a discharge in the lamps 5 and. 6..

Upon the initiation of this discharge, the v'oltage drop across the lamps 5 and iii; such that the condenser 8 in electrical series relationship with the discharge lamp 5 to give it a leading power factor, while that of lamp 6 has a lagging power factor to thus neutralize the stroboscopic effect and at the same time correct the overall -35 and inductance element 36 to the electrode 31 of lamp 6 and thence through the ensuing discharge to the electrode 39 and back to' the other side of the supply source L2 by means of conductor 32 and switch 33. Similarly the operating circuit for the leading power factor lamp 3 extends from one side of the supply source Ll through inductance l8, conductor 20, closed" contacts l3-9 'of the transfer switch 1, conductor 28 to one side of condenser 8 and from the other side, by means of conductors 21 and 28, to the electrode 23 of the lamp 5, and thence through the ensuing discharge to the electrode 38 and back to the opposite side of the supply source L2 through conductor 32 and switch 33.

From the foregoing it thus becomes obvious to one skilledin the art that a system for controlling and operating discharge lamps particularly of the fluorescent type is herein provided so that a pair of such lamps can be immediately started with a minimum of time delay, and once started the system operates so that the stroboscopic effect otherwise ensuing is minimized. This is accomplished by employing a condenser which is connected in electrical parallel with the lamps during starting, and by the automatic operation of a transfer switch, such condenser is connected in series relationship with one of the lamps during operation. 7

Although one specific embodiment of the present invention has been herein shown and described, it is to be understood that other modifications thereof .may be made without departing to facilitate the initiation of a discharge thereinand automatically operable to thereafter cause the voltage impressed upon the magnetic winding .25- of the transfer switchfl' is insufilcient to retain the armature in its attracted position, with theresult that the spring. l3, aided by gravity causes the rod I 8 to drop to the position as shown in Fig. 3. Such movement accordingly alters the relationshipof the various contacts toplace them in "operating position and specifically connects 18 other of its contacts to connect said energy storage means in'series with one of said lamps to minimize the stroboscopic effect and improve the overall power factor of said system. I

2. A system for starting and operating a pair 'of discharge lamps comprising an energizing circuit, a'switch operable by an operator for closing said circuit, a condenser adapted to be connected to said energizing circuit, and a relay connected to said circuit upon closure of said switch and initially operable to connect said condenser in said energizing circuit in electrical parallel relation'with said lamps to facilitate starting of a discharge therein, and said relay being automatically operable upon initiation of the discharge in said lamps to connect-saidcondenser in series relation with one of said'lamps to minimize the trical energy, switch means operable at will to cause energization of said lamps from said source, energy storage means adapted to be connected to said source and to said lamps, a relay connected to said source upon operation of said switch means. and contact connections operable by said relay upon energization thereof to sequentially connect said energy storage means in electrical parallel relation with said lamps to facilitate the initiation of a discharge therein and for there'- after connecting said energy storage means in serice with one of said lamps during the continuance 01' a discharge in said lamps to minimize the stroboscopic efl'ect with attendantoverall'power factor correction.

4. A system for starting and operating a pair of discharge lamps comprising a source of electrical energy, switch means operable at will to cause energization of said lamps from said source, energy storage means adapted to be connected to said source and toy said lamps, and a relay provided with a plurality of contacts and having a magnetic winding connectable in electrical parallel with said lamps upon closure-of said switch meansand enersizable by the full voltage of said source to cause some or said contacts to connect said energy'storage means in electrical parallel with said lamps to facilitate the initiation of a discharge therein, and said relay being thereafter operableupon' the application oi lamp voltage to said magnetic winding following initiation of the discharge'in said lamps to connect said energy storage means in series with one of said lamps for the purpose of minimizing the stroboscopic eflect and improving the overall power factor of said CHARLES H. nonaxms,

system 

